import math
  
def floatinput():
    a = input().split()
    for i in range(len(a)):
        a[i] = float(a[i])
    return a
     
def main():
    a = floatinput()
    x1 = a[0]; y1 = a[1]; x2 = a[2]; y2 = a[3]
    print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))
     
if __name__ == "__main__":
    main() import math math def floatinput():
    a = input().split()
    for i in range(len(a)):
        a[i] = float(a[i])
    return a
      floatinput a = input().split() a input().split() ().split () input split for i in range(len(a)):
        a[i] = float(a[i])
     i range(len(a)) range len(a) len a a[i] = float(a[i]) a[i] a i float(a[i]) float a[i] a i return a a def main():
    a = floatinput()
    x1 = a[0]; y1 = a[1]; x2 = a[2]; y2 = a[3]
    print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))
      main a = floatinput() a floatinput() floatinput x1 = a[0] x1 a[0] a 0 y1 = a[1] y1 a[1] a 1 x2 = a[2] x2 a[2] a 2 y2 = a[3] y2 a[3] a 3 print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)) print math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2) math.sqrt math sqrt (x1 - x2) ** 2 + (y1 - y2) ** 2 (x1 - x2) ** 2 x1 - x2 x1 x2 2 (y1 - y2) ** 2 y1 - y2 y1 y2 2 if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def floatinput():
    a = input().split()
    for i in range(len(a)):
        a[i] = float(a[i])
    return a
      def floatinput():
    a = input().split()
    for i in range(len(a)):
        a[i] = float(a[i])
    return a
      floatinput def main():
    a = floatinput()
    x1 = a[0]; y1 = a[1]; x2 = a[2]; y2 = a[3]
    print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))
      def main():
    a = floatinput()
    x1 = a[0]; y1 = a[1]; x2 = a[2]; y2 = a[3]
    print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))
      main
import math
  
def floatinput():
    a = input().split()
    for i in range(len(a)):
        a[i] = float(a[i])
    return a
     
def main():
    a = floatinput()
    x1 = a[0]; y1 = a[1]; x2 = a[2]; y2 = a[3]
    print(math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))
     
if __name__ == "__main__":
    main()
